Uplink

Pertaining to satellite communications, an uplink (UL or U/L) is the portion of a communications link used for the transmission of signals from an Earth terminal to a satellite or to an airborne platform. An uplink is the inverse of a downlink. An uplink or downlink is distinguished from reverse link or forward link.
Pertaining to GSM and cellular networks, the radio uplink is the transmission path from the mobile station (cell phone) to a base station (cell site). Traffic and signalling flows within the BSS and NSS may also be identified as uplink and downlink.
Pertaining to computer networks, an uplink is a connection from data communications equipment toward the network core. This is also known as an upstream connection.